The Great 5V 40mm Shoot-Out Comparison

To cut down your electricity bill and to continue crunching you can stick with x86 CPUs and buy in the 10Watt-25Watt TDP range, or you can step into ARM crunching.
You can even try to be at the very cutting edge of low-power IT and try to get BOINC running on RISC-V, but you have to do a lot of things yourself that way.

The ARM crunching came into being for two things: Android hardware and Raspberry Pi SBCs. For both approaches cooling becomes essential if you not only want relatively cheap crunching, but performance as well.

Many SBC cases and aftermarket cooling solutions center on the use of 5V fans for the active part of cooling, or small lumps of aluminium for the passive part of it. If overheating of the SOC is holding you down you'd best stick some more heatsinks on the hot parts, or direct a flow of cool air over them -even if you have to break open that Android TV box. If you still have problems you need a bigger hammer, pardon: heatsink, and/or a better fan. As some of the fans I use are pathetically small -30mm- I searched for a review of 40mm fans, and found this review Raspberry Pi 4 - 40mm Fan Comparison, which has this conclusion:

Quote:

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Based on your primary requirement fan selection can be presented as:

1. Thermal performance: Sunon MF40100V1 @5V
2. Minimal noise (no cost limits): Noctua NF-A4x10 @3.3V
3. Balanced option (thermal/noise/cost): Sunon MF40100V2 -at either 5V or 3.3V

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Which under the parameters of the review is a perfect conclusion, but which leaves out other parameters. 'Cost' in my opinion is more than purchase, there are also running costs, i.e., your lecky bill. And perhaps not surprisingly that -on purchase- very expensive Noctua fan is actually the cheapest running solution! The Noctua fan actually uses 53mA @5V and 33mA @3.3V (see the comments) and no other fan even comes close. But there are even more parameters around, as shown here:

Quote:

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1. If you want a fan for installation in a case, pick something with high CFM (Cubic Feet per Minute, in rest-of-world cubic meter/h)
2. For the best results on coolers and water-cooling radiators, aim for high static pressure (in mmH2O).
3. If possible, pick 140-mm fans.
4. Don't trust manufacturer data about noise levels. Check group tests where a sound level meter has been used.
5. Think through what RPM level is best for you.
6. Aim for Ball / FDB / SSO or magnetic levitation (MagLev) bearings.
7. Make sure you know which RGB ecosystem your fans are compatible with.

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As I could not find a good 40mm fan review I will wave rule 4, so bear in mind that the below column 'dba' has to be taken with a healthy pinch of salt: these are all manufacturers figures. As some companies have datasheet saying so many Amps or Watts and print their fan labels with other values, I give them both where applicable. I also present Airflow and Air Pressure in both imperial and rest-of-world values, so that anybody can understand what is printed. So I hereby present to you:

The Great 5V 40mm Shoot-Out Comparison
https://i.postimg.cc/gwDSkdVL/40mm-s...2022-04-05.jpg Click on the image for a full view!
If I have missed a fan: just mention it and I will update the table.

Recommendations (note these are all 20mm thick/deep fans):

1. Thermal performance: CUI CFM-4020CF-095-342 (2-pin) and CUI CFM-4020BF-095-342-20 (3-pin)@5V -provided you can stand the noise and can pay the lecky bill @2.0(2-pin)/2.25(3-pin) Watt
2. Minimal noise (no cost limits): Noctua NF-A4x20 (3-pin) and Noctua NF-A4x20 PWM (4-pin) @3.3V -running costs @0.5Watt are also much lower than the fans above
3. Balanced option (thermal/noise/cost): Sunon MF40200V3 and CUI CFM-4020V-050-165 at either 5V or 3.3V

If you only have room for a 10mm thick/deep fan:

1. Thermal performance: Sunon MF40100V1 and CUI CFM-4010V-070-273 @5V
2. Minimal noise (no cost limits): Noctua NF-A4x10 (3-pin) and Noctua NF-A4x10 PWM (4-pin) @3.3V
3. Balanced option (thermal/noise/cost): Sunon MF40100V2 and CUI CFM-4010V-058-206 at either 5V or 3.3V